Fusarium wilt pathogens represent an ongoing threat to pepper production worldwide. This is the first report providing data on the molecular identification of Fusarium fungi that cause wilt in pepper in the southern regions of Russia. Monitoring of the Fusarium infection on pepper was carried out in 2019–2022 in two economically important regions of this culture production: the Krasnodar Krai and Crimea. Based on a phylogenetic analysis of the translation elongation factor (EF1a) and the internal transcribed spacer (ITS), as well as the macro- and micromorphological characteristics of the fungi, the causative agents of Fusarium wilt have been identified. The causative agents identified as representatives of the Fusarium species composition included: F. clavus, F. solani, F. oxysporum, F. verticillioides, F. commune, F. torulosum, and F. sporotrichioides. Depending on the region, the specifics of biodiversity and the ratio of these species in pathocomplexes were noted. In Crimea, wilting could be attributed to all of the identified species; in the Krasnodar Krai, F. verticillioides and F. clavus were found to contribute to wilting. The pathogenicity test showed that the pathogens of pepper wilting in Russia, in addition to the already known F. oxysporum and F. solani, are the species F. clavus and F. verticillioides. This is the first report on the ability of these species to cause Fusarium wilt in pepper cultures. The obtained data will be of practical value for the development of biological control measures for fungi of the genus Fusarium, which cause pepper wilt in areas of industrial production and seed production. In addition, data on species composition and aggressive isolates will be used in a pepper breeding program for resistance to Fusarium wilt.

Fusarium basal rot of onions causes large losses during storage of commercial production of onion bulbs, which in turn adversely affects the food market situation in the off-season period. There are no data on the composition of Fusarium spp., which causes onion basal rot in the Russian Federation. Therefore, our research was aimed at Fusarium spp. causing onion basal rot in the Moscow Region of the Russian Federation and studying the pathogenicity of these species for the host plant. We studied 20 isolates of Fusarium spp. collected from affected mature bulbs and seed bulbs. Species identification of the isolates was carried out using analysis of the nucleotide sequences of the three genetic loci ITS, tef1 and rpb2, as well as was based on the macro- and micromorphological characteristics of these isolates. As a result, the species F. annulatum (F. fujikuroi species complex), F. oxysporum (F. oxysporum species complex), F. acuminatum (F. tricinctum species complex) and F. solani (F. solani species complex) were identified to involve in the pathogenesis of Fusarium basal rot. We have shown for the first time that the species F. annulatum and F. acuminatum are highly aggressive and capable of causing onion basal rot. The predominant species were F. annulatum and F. oxysporum. The proportion of these species in the total number of analyzed isolates was 60% and 25%, respectively. The largest proportion (33%) of highly aggressive on mature bulbs isolates was found in the species F. annulatum. The data obtained provide practical insights for developing strategies to manage Fusarium fungi responsible for onion basal rot Moscow Region of the Russian Federation. In addition, data about species composition and aggressive isolates may be used in onion breeding for resistance to Fusarium basal rot.

Fusarium wilt of melon, caused by Fusarium fungi, results in sizeable economic losses worldwide. In Russia, data on the species composition of the causative pathogens of this disease on melon are lacking. From 2022 to 2025, 19 Fusarium isolates from the Volgograd and Rostov regions were included in a study that included species identification using molecular phylogenetic analysis of the tef1 and rpb2 loci, morphological description, and pathogenicity assessment against the host plant and other members of the Cucurbitaceae family. Four Fusarium species were found to be involved in the pathogenesis of Fusarium wilt of melon in Russia: F. clavus (37% of the total number of isolates), F. annulatum (21%), F. cf. inflexum (21%), and F. brachygibbosum (21%). All identified species were isolated in the Volgograd Region, while only F. cf. inflexum and F. brachygibbosum were isolated in the Rostov Region. This study reports for the first time the high pathogenicity of F. cf. inflexum and F. brachygibbosum species associated with melon wilt. Morphological variability and different aggressiveness of isolates of the species F. brachygibbosum and F. clavus, isolated in the Volgograd (-V) and Rostov (-R) regions in different years, were observed. The isolate F. brachygibbosum-V showed high aggressiveness both at the sprout and seedling stages, while the isolate F. brachygibbosum-R was characterized by moderate aggressiveness only at the sprout stage. High pathogenicity of the species isolated from melons was established for other cucurbit crops. F. cf. inflexum was also pathogenic for watermelon and pumpkin, and F. brachygibbosum was pathogenic for pumpkin. The obtained data will have practical value for the development of biological control measures against Fusarium fungi and will be used in a melon breeding program for resistance to Fusarium wilt.

Fusarium fungi are known to infect table beet (Beta vulgaris subsp. vulgaris) plants at various stages of development worldwide. Fusarium root rot, which develops post-harvest during long-term storage, is of particular economic significance. In Russia, there is no up-to-date information about the species diversity of pathogens causing this disease of table beets, which determined the purpose of this study. A total of 28 Fusarium isolates were collected from affected beet roots grown in the Moscow region of the Russian Federation from 2018 to 2023 years. Molecular phylogeny based on the TEF-1α and RPB2 genes in combination with morphological characterization showed that five Fusarium species were involved in the pathogenesis of Fusarium root rot of table beet during storage: F. acuminatum (43% of the total number of isolates), F. avenaceum, F. campestre (FTSC); F. sporotrichioides (FSAMSC) and F. solani (FSSC). At the same time, the species F. acuminatum, F. campestre, and F. sporotrichioides were first discovered on beet root in the Russian Federation. Temperature sensitivity of the identified species was studied at 5 °C and 25 °C. According to the value of the cold sensitivity index (CTI) on the nutrient medium and native substrate, the isolates were distributed differently: F. campestre (0.32) > F. acuminatum (0.22) > F. avenaceum (0.21) > F. sporotrichioides (0.19) > F. solani (0.20) and F. acuminatum (0.32) > F. campestre (0.21) > F. solani (0.03) > F. avenaceum and F. sporotrichioides (0.01), respectively. This confirms the need to study the pathogenic properties of isolates on a natural substrate (host plant) under different temperature conditions. When infected with the dominant and most aggressive species F. acuminatum, there was a high variation in the size of the affected area, depending on the genotype of the lines, under both temperature conditions (Va = 2–8 mm³ at 5 °C and Va = 31–1760 mm³ at 25 °C). Therefore, this species can be considered to be the most objective differentiating factor in assessing the resistance of table beet roots to fusarium rot, which determines the need to include it in the breeding process for creating resistant varieties and hybrids for the Central region of Russia. The data obtained in this study are of great importance for developing strategies for managing Fusarium fungi associated with Fusarium rot of beet-root during storage. The research results will also be relevant for other vegetable crops that remain fresh for long periods of time or undergo vernalization in the case of seed production at low temperatures.

Изучен полиморфизм первичной структуры генов семейства ipiO в популяции Phytophthora infestans в Московской области. В качестве метода оценки полиморфизма использовали SSCP-анализ. В результате при помощи этого метода удалось различить классы генов семейства ipiO и установить, что изучаемые образцы имели один из трех вариантов генотипа ipiO в зависимости от комбинации у них генов этих классов. Выявленные генотипы оказались распределены в проанализированной популяции P. infestans Московской области с неодинаковой частотой. Кроме того, было показано, что картофельная и томатная субпопуляции P. infestans также различаются по частотам встречаемости выявленных генотипов.